a quick demo of how to code 99 beers on the wall in js

ninety9beers.js

(function(){
  var arr = [],

      START_COUNT = 99;
      TPL = '%count bottles of beer on the wall, %count bottles of beer, take 1 down, pass it around, %nextCount bottles of beer on the wall\r\n';

  function init () {
    for (var i = START_COUNT; i > 0; i--) {
      arr.push(hydrate({count: i, nextCount: i-1}));
    }

    console.log(arr.join(''));
  }

  function tokenize() {
    var tokens = [];

    TPL
      .match(/%\w+/g)
      .unique()
      .forEach( function(tokenName, k) {
        tokens.push( {regEx: new RegExp(tokenName, 'g'), variable: getVariableName(tokenName)} );
      });

    return tokens;
  }

  function getVariableName(tokenName) {
    return tokenName.slice(1);
  }

  function hydrate(ob) {
    var tokens = tokenize(),
        hydratedTpl = TPL;

    tokens.forEach(function(token){
      hydratedTpl = hydratedTpl.replace(token.regEx, ob[token.variable]);
    });

    return hydratedTpl;
  }

  // a little brute force
  Array.prototype.unique = function unique () {
    return this.reduce(function(prev, curr){
      if (!~prev.indexOf(curr)) prev.push(curr);
      return prev;
    }, []);
  };

  init();

})();